The housing of a battery functions to retain and protect the electrochemically active components of a battery stack while also allowing for extraction of electrical power therefrom. The battery housing isolates the electrolytes and other potentially reactive components of the battery from oxygen, moisture, and other detrimental components of an ambient atmosphere. A battery housing should be lightweight and rugged, and its use and fabrication should be simple and inexpensive to implement. Furthermore, the housing should be configured to facilitate the assembly of power systems comprised of a plurality of battery modules, while optimizing the management of thermal loads.
In some instances, battery components are disposed in flexible polymeric packages. While housings of this type are lightweight and low in cost, such packages tend to be permeable to moisture and oxygen, and problems are also encountered at the points at which electrode tabs or other structures must protrude from the package to allow for tapping of electrical current. Furthermore, such flexible packages can not readily be configured in stacked configurations. As such, such flexible packages are not generally employed in electrical vehicles and other such high power and/or long service life applications.
Metal battery housings can establish a superior seal against atmospheric contaminants while providing high strength, good thermal dissipation, and good electrical contact to battery components. However, certain problems do arise in connection with the use of metal battery housings. In general, cylindrical battery housing structures are relatively easy to fabricate. However, cylindrical battery structures do not provide for maximum packing density as may be required in electrical vehicle applications.
In some instances, battery housings are configured as prismatic structures which are understood to mean structures having a polygonal, and typically rectangular, profile. Such battery structures allow for high volume packing which maximizes power density. In addition, the relatively large exterior surface area allows for very good heat dissipation. Cost has been a significant problem, which has limited the use of such prismatic battery structures since their construction typically requires the use of relatively expensive, deep drawn metal structural components. In addition, sealing of such structures is typically required to be implemented by relatively expensive processes such as laser welding.
As will be explained hereinbelow, the present invention provides for an improved battery structure which employs a prismatic battery casing which can be fabricated without the use of any deep drawing or other expensive metal fabrication process. In addition, the battery housing of the present invention is configured so that it can be assembled utilizing relatively low cost crimping or hemming techniques. Furthermore, the housing of the present invention is configured to permit ready stacking of individual battery modules into power configurations, while minimizing interconnections and optimizing management of heat loads. These and other advantages of the present invention will be apparent from the drawings, descriptions, and discussion which follow.